Embodiments relate to vibrating actuator assemblies, and more particularly, to a vibrating actuator assembly capable of generating strong driving power by employing a compact structure and implementing precise position control, and a digital image processing apparatus including the same.
Optical systems including optical components, such as lenses, include lens driving mechanisms to move the lenses. The lens driving mechanisms perform a zooming function or an auto focusing function by changing relative distances between the lenses by moving the lenses.
Such conventional lens driving mechanisms may use a driving unit such as a stepping motor, and a reduction gear and a cam are used to change rotation of the stepping motor to a straight movement, and the size is increased and the structure becomes complex. Furthermore, an error may be generated due to a backlash during normal rotation or reverse rotation, power consumption may be increased, a high current may be required, and heat may be generated.
Recently, piezoelectric devices operating according to a piezoelectric effect are widely applied to move the lenses of the optical systems. Subminiature driving motors may be manufactured by using the piezoelectric devices.
However, in general optical systems using a piezoelectric device, since mechanical components, such as a gear or a cam, are used to convert a transformation movement of the piezoelectric device to driving power for moving lenses, a structure becomes complex and it is difficult to implement accurate position control due to an error between the mechanical components.
U.S. Pat. No. 5,892,317 discloses an actuator realizing a rotation movement of a moving element according to vibration of piezoelectric devices. According to the disclosed actuator, the moving element contacting an elastic body is rotated by transmitting vibration of the piezoelectric devices generated by applying an electric signal to the piezoelectric devices disposed on one surface of a rotor to the elastic body to deform the elastic body.
However, since the moving element is driven by using the elastic body and the piezoelectric devices are only disposed on one surface of the moving element, the piezoelectric devices have to self-generate a vibration movement of traveling waves. In this case, space efficiency is decreased since sections are classified by asymmetrically disposing the piezoelectric devices in a circumferential direction, and it is difficult to design and manufacture the actuator since intervals between the piezoelectric devices and lengths of the piezoelectric devices need to be precisely maintained.
Also, in order to effectively rotate the moving element, a protrusion on one surface of the elastic body that transmits force by frictionizing with the moving element needs to have predetermined rigidity, but the rigidity of the protrusion adversely affects the elastic body and the piezoelectric devices, and thus overall driving performance and a control performance are deteriorated. Also, in order to rotatably support the moving element, a separate bearing is provided, and thus an overall size of the actuator is increased. Also, performance of products may vary or operation noise may be generated according to variation in precision of the bearing.
In addition, since performance may vary according to assembled states of support structures when the actuator is assembled, a vibration movement by traveling waves generated in the piezoelectric devices may be deformed or resonance may be generated as vibration is transmitted to and reflected from other components.